1. Field of the Invention
The present invention relates to a waste water treatment equipment for treating sewage containing solid wastes left after crushing garbage sent out from cooking room, home kitchen and the like, or waste water sent out from water closet, bath and the like.
2. Description of Prior Art
With regard to equipment for treating sewage sent out from home water closet, kitchen, bath, etc., several attemps have been proposed as disclosed in Japanese Patent Publications (examined) SHO 60-29319 and HEI 1-60313. That is, the Japanese Patent Publication SHO 60-29319 disclosed a sewage treatment equipment to perform a series of operations comprising the steps of: removing relatively large materials insoluble or difficult to be dissolved from the sewage sent out from home water closet by introducing the sewage in a screen of large meshes; compressing fine suspended solid (hereinafter referred to as "SS") in the sewage by compressor having very fine filter medium thereby separating the SS and removing 85 to 98% of water therefrom; supplying the dewatered SS into a SS deposit tank; introducing the sewage filtered through the mentioned fine filter medium into an aeration tank in which sponge activated sludge process beds are vertically provided to perform aeration for decomposition of water pollution materials such as BOD, COD in the sewage water by oxidation; and disinfecting the materials by chloride. When employing such prior sewage treatment equipment, as a result of forcibly removing large SS and fine SS in the steps of earlier half of the treament, BOD concentration in the sewage is reduced to about 50 ppm, and this BOD concetration is finally reduced to not more than 3 ppm by the treatment of low load performed in the steps of latter half in the activated sludge process beds and disinfection by chloride. Then, the Japanese Patent Publication No. HEI 1-60313 discloses a sewage tratment equipment to perform operations comprising the steps of: introducing sewage sent out of home water closet, kitchen, etc. into a solid waste removing device to crush solid wastes or materials condensed in the sewage; separating and removing large solid wastes; introducing the sewage whose large solid waste have been removed sequentially into a plurality of sewage treatment tanks formed by vertically providing activated sludge process beds above the aeration tank disposed on the bottom, each of the activated sludge process beds being formed of an elongated cylindrical core of which grid-like outer periphery is wrapped with a porous member of certain thickness; changing shapes of the activated sludge process beds each vertically provided in each of the sewage treatment tanks; performing treating operations starting from a treatment of high load to that of low load in said plurality of sewage treatment tanks; causing the sewage thus treated to flow sequentially in a settling tank and a disinfecting tank; and draining the treated sewage of not more than 3 ppm.
Any of the above sewage treatment equipment disclosed in the Japanese Patent Publications SHO 60-29319 and HEI 1-60313 exhibits high performance of purification, however, have several disadvantages. In case of the sewage treatment equipment disclosed in the Japanese Patent Publication SHO 60-29319, a compressor with a very fine filter medium is employed in the earlier half of the treatment. This compressor is operated to forcibly remove very fine SS thereby BOD concentration of the filtered sewage is reduced to a certain extent and then required treatment of low load takes place in the aeration trank with active sludge process bed. Accordingly, the compressor is intricated in its construction and has many movable parts, and moreover is provided with very fine filter medium. As a result, there arise such disadvantages as troublesome maintenance and operation taking much labor and long time, easy occurrence of trouble, etc.
In any of the sewage treatment wquipment disclosed in the Japanese Patent Publications SHO 60-29319 and HEI 1-60313, there still remain further disadvantes in the aspect of treating sewage containing solid wastes left after crushing gasbage sent out from cooking room, home kitchen, etc. More specifically, when treating a sewage containing solid wastes by means of compressor, the dewatered solid wastes are delivered to the reservoir, or relatively large solid wastes and fibrous materials left after crushing garbage in the sewage introduced in the solid waste removing device are accumulatively deposited in the solid waste reservoir, and these deposited solid wastes separately need additional troublesome treatments.